1. Field of the Invention
The present invention relates to backlight modules used in liquid crystal displays and, particularly, to a backlight module having a specially constructed reflective surface.
2. Discussion of Related Art
In a typical liquid crystal display, a backlight module provides a surface light source for illuminating the liquid crystal display. Generally, the backlight module includes a light guide plate and a light source arranged adjacent to one side of the light guide plate. The light guide plate changes light beams received from the light source (e.g., a point or linear light source) into surface/area light beams and directs such surface light beams to a liquid crystal panel of the liquid crystal display.
FIGS. 5 and 6 show a conventional backlight module 10. The backlight module 10 includes a light guide plate (LGP) 14 and a point light source 12 adjacent to the LGP 14. The LGP 14 includes an incident surface 142, an emitting surface 144 adjacent to the incident surface 142, a reflecting surface 146 opposite to the emitting surface 144, and three side surfaces (not labeled). The LGP 14 changes light beams received from the point light source 12 into surface light beams and directs surface light beams out of the emitting surface 144.
To improve the uniformity and efficiency of illumination of the backlight module 10, a number of microstructures 162 are arranged on the reflecting surface 146. The microstructures are concentric relative to the point light source 12. In operation, light beams emitted from the point light source 12 propagate within the LGP 14 toward the microstructures 162, in directions perpendicular thereto. Light beams are reflected and/or refracted at the microstructures 162 and are emitted from the emitting surface 144. Due to the distribution of microstructures 162, the diffusion of the light beams is reduced (i.e., the wasting of the light beam is decreased), the transfer efficiency of the LGP 14 is enhanced, and, thus, more surface light beams are emitted from the emitting surface 144.
However, there is ongoing demand for backlight modules to provide an even more improved brightness and uniformity of illumination. A new backlight module that can meet this demand is desired.